[DeTomaso] Thermostat restrictor plate 351 C

Wed Jun 11 01:33:17 EDT 2014

Thank You Asa Jay Laughton - I am going to digest what you sent and MAYBE I can ask better questions;  My concern is trying to understand the "bypass" mechanism/concept. I have a weiand water pump, which apparently has no bypass - I have to try and understand this. I m going to digest as much as I can from your writing. The first thing I am going to do is pull the thermostat housing and "see what I have". Very Good!!! 
Jack
4348
On Jun 10, 2014, at 7:05 PM, Asa Jay Laughton <asajay at asajay.com> wrote:

> Third time is a charm?
> 
> Hi John,
> I've been monitoring the replies all day; didn't get a chance to reply
> until I got home.
> 
> I think what's missing here is the bigger picture.  "Why are you asking
> this question?  What is the problem you are trying to solve?"
> 
> Even if you're just after some head knowledge I'm hoping what follows
> will be useful.  :)
> 
> Most people continue to have a 351C (Cleveland) in their Pantera.  Some
> have substituted a 351W (Windsor) while some later Panteras came with
> them stock; others have put various other makes and model engines in. 
> We'll confine this dissertation to the 351C as it's the most common and
> is the reason the whole "restrictor plate" question comes up.
> 
> The 351W does not use a restrictor plate, so we'll just take it off the
> table completely.
> 
> The restrictor plate is actually a bypass "helper."  It's a round piece
> of metal with a large hole in the middle.  During warm up of the engine,
> some coolant goes through this hole bypassing the radiator and
> recirculating immediately to the engine.  This is of course assuming one
> has a stock style water pump and -not- one that has the bypass passages
> sealed off.
> 
> Once the thermostat opens, and you are using the proper thermostat, the
> passage becomes very restricted and there is virtually no coolant flow
> bypassing the radiator anymore, though a small amount still does.
> 
> Here are the photos.
> This is a restrictor plate in it's factory original position.  You can
> see it's installed in a recess cast into the block deep inside the
> thermostat port.  When the thermostat is closed, no coolant goes out the
> top of the block but it has to go somewhere or it just boils in place. 
> It goes through the small hole in the restrictor plate and into the
> water pump:
> http://teampanteraracing.com/index.php?option=com_g2bridge&view=gallery&Itemid=57&g2_itemId=2639
> 
> You asked about a photo of the front cover without a water pump
> attached.  Let me go one better.  Here is a photo of a long wire-tie
> going through the top of the bypass hole and existing the front of the
> block at the water pump bypass port:
> http://teampanteraracing.com/index.php?option=com_g2bridge&view=gallery&Itemid=57&g2_itemId=3077
> 
> The water pump port it goes into is shown in this next photo.  What you
> have to pay close attention to is that the bypass goes -two- ways; one
> is toward the heater core, shown by the wire-tie exiting the heater hose
> port, the other is behind the wire-tie as you see it and leads directly
> to the water pump impeller; you can just see the open hole behind the
> wire-tie:
> http://teampanteraracing.com/index.php?option=com_g2bridge&view=gallery&Itemid=57&g2_itemId=3071
> 
> The coolant that goes to the heater core also travels back into the
> block at the other heater hose port and you can see with this photo how
> it ends up just over the top of the restrictor plate:
> http://teampanteraracing.com/index.php?option=com_g2bridge&view=gallery&Itemid=57&g2_itemId=3080
> 
> Please note I don't really know which way the coolant is flowing through
> the heater core in either position of the thermostat; all I did was
> illustrate the path.
> 
> Within the water pump, the bypass flows back into the engine through the
> larger two ports after passing by the impeller.  I'm sorry I don't have
> a photo of that, but found one on the Internet:
> http://i.ebayimg.com/00/s/MTA2M1gxNjAw/z/MysAAMXQySpRS8if/$T2eC16N,!yUE9s6NDMc9BRS8ie8NuQ~~60_35.JPG
> 
> This is the back side and it mates up to the front of the engine that
> looks like this:
> http://image.mustangandfords.com/f/58890193+w650+h650+cr1/aluminum-351-cleveland-double-roller-timing-chain-1.jpg
> 
> By the way, that's a new ALUMINUM 351C block (by Todd Buttermore)
> Anyway, on the left, you see a large square port and above and to the
> right you see a round port, just below another round port that is for
> the temp sender, right below where the thermostat goes.  The two large
> squarish ports are the INLET to the block from the water pump.  The
> smaller round hole is the BYPASS OUTLET to the water pump.
> 
> Now, if you have a water pump that has no bypass port, like the one
> below, then the restrictor plate doesn't matter much because as
> illustrated with the wire-tie earlier, there's no place for the coolant
> to go:
> http://www.supermotors.net/getfile/802687/fullsize/8209impeller.jpg
> 
> But let's say you have a standard water pump with bypass.  Alright, so
> the thermostat has opened, and if  you have the correct thermostat it
> should block the flow of coolant to the bypass port.  Here we see what a
> proper 351C thermostat should look like, see the little "hat" on the
> bottom?:
> http://teampanteraracing.com/index.php?option=com_g2bridge&view=gallery&Itemid=57&g2_itemId=2645
> 
> I've got a screwdriver shoved in there to open it so you can see the
> "hat" better.  Next, I ripped that thermostat apart just so I could
> create this photo where you can see the "hat" sits in the large hole
> restricting the flow through the bypass:
> http://teampanteraracing.com/index.php?option=com_g2bridge&view=gallery&Itemid=57&g2_itemId=2657
> 
> So with the bypass essentially closed, now the coolant circulates
> through the thermostat, through the radiator, back to the water pump and
> back into the engine.  It can also pass through the heater hoses and
> heater core as that path through the water pump is -not- blocked; it's
> just not passing through the bypass port anymore.
> 
> Here is a photo of an IPSCO or Marlin Jack restrictor plate compared to
> a stock one:
> http://image1.cougparts.com/sc/images/10003234_2.jpg
> 
> The recess in the IPSCO model is to accommodate the regular thermostat
> opening.  The small hole is helpful for getting air out of the system
> and also allows a minuscule amount of coolant through; I would venture
> negligible for warm-up purposes.
> 
> If you did not have a restrictor plate, then I think you'd be chasing a
> constant overheating problem.  Are you?  If not, then I think your
> restrictor plate may be in place.  It's easy enough to check, well....
> not -that- easy on a Pantera as you have to get in there typically from
> the passenger compartment, but two bolts to undo the housing, lift the
> thermostat out and there you go, is it there or not.
> 
> If on the other hand you see this:
> http://www.351c.info/gallery2/v/asajay/351C_Build_2001/stat.jpg.html
> That means you have a 400 and NOT a 351C, which is very doubtful.  Note
> this photo does not have a recess for the restrictor plate, the
> restrictor is actually -cast- into the block.
> 
> On another occasion in a different engine, I decided to plug the
> restrictor plate hole, you can read about how I did that on the same
> Team Pantera Racing web site I linked to most of the other photos. 
> There is more there from the TPR division of the Pantera Research
> Institute, browse around and if you have any questions, let us know.
> 
> Hopefully this has been helpful,
> Asa  Jay
> 
> -- 
> Asa Jay Laughton, MSgt, USAFR, Retired
> & Shelley Marie
> Spokane, WA
> ******************************     
> http://www.racingagainstautism.com
> http://www.teampanteraracing.com
> http://facebook.com/racingagainstautism
> 
> 
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